Definition
Rain that falls as a liquid through a layer of below-freezing air and freezes on contact with any surface whose temperature is at or below 0 °C (32 °F). It typically forms when warm, moist air aloft overlies a shallow layer of sub-freezing air near the ground, producing clear, glaze-type ice on aircraft, runways, and other exposed surfaces.
Plain English
Rain drops that are still liquid when they hit something cold and then freeze instantly into a smooth layer of ice.
Context Anchor
Seen in instrument weather planning, icing discussions, forecasts, and pilot weather reports when deciding whether a route is safe to fly.
Why Pilots Care
It rapidly builds heavy, smooth clear ice on wings, tail, and windshield, severely reducing lift and visibility and often forcing an immediate change of altitude or route.
Grounding Statement
Picture liquid raindrops hitting a wing that is below freezing and turning into a clear coat of ice almost immediately.
Intuition Check
Freezing rain is not rain that is already frozen as it falls. It is liquid rain that freezes on contact with a cold surface.
Example Sentence 1
The PIREP reported freezing rain at 4,000 feet, so the crew climbed to a warmer layer to stop ice accumulation on the wings.
Example Sentence 2
Preflight inspection revealed clear ice on the leading edges after the aircraft had been parked in freezing rain.